循序渐进PostgreSQL: 学习pqxx C API访问

习惯了C 来开发的人，可能更倾向于使用c 库来访问PostgreSQL。libpqxx很早以前就推出了。目前已经到了4.0版。本文就简单的介绍

1. 简介

习惯了C 来开发的人，可能更倾向于使用c 库来访问PostgreSQL。libpqxx很早以前就推出了。目前已经到了4.0版。本文就简单的介绍如何使用它，，Linux平台编译相对简单，这里就介绍一下Windows平台下的使用。

libpqxx的下载地址：直接上这里

由于libpqxx对libpq的C-API进行了很好的封装，从而可以节省大量的编码时间。

2. 编译过程

将libpqxx解压到一固定目录。你需要提前编译好或安装好的客户端库，通常为了方便，这里假定你已经有一个PG的安装版或者解压缩版，在c:pgsql里头。以PG9.x为例。

1. 进入libpqxx源码目录，备份并修改win32common文件，将PGSQLSRC的值指向正确的地方：

这里是PGSQLSRC="c:pgsql"

后边还有很多目录位置需要调整，针对我们这种情况，通常都是保留安装版本的设置，如：LIBPQINC=$(PGSQLSRC)include, 而注释掉#LIBPQINC=$(PGSQLSRC)interfaceslibpq, 其它几个值都如此类推。

2. 拷贝一些编译相关的头文件

针对具体版本，9.0的，将configsample-headerslibpq9.0pqxx复制到include下边

针对VS2008的，将configsample-headerscompilerVisualStudio2008pqxx复制到include目录下边, 如果是VS2005，以此类推。

3. 编译

program files->VS2008-->Visual studio tools->Visual Studio 2008 Command Prompt, 进入命令行， 在此进入libpqxx的源代码根目录，执行：

nmake /f win32vc-libpqxx.mak ALL,

得到如下中间过程:

link.exe kernel32.lib ws2_32.lib advapi32.lib /nologo /dll /machine:I386 
 shell32.lib secur32.lib wldap32.lib /libpath:"C:hisql-x86-2.0.1"lib libpq.lib 
  "ObjDllReleasebinarystring.obj"  "ObjDllReleaseconnection.obj"  "ObjDllRelea 
seconnection_base.obj"  "ObjDllReleasecursor.obj"  "ObjDllReleasedbtransactio 
n.obj"  "ObjDllReleaseerrorhandler.obj"  "ObjDllReleaseexcept.obj"  "ObjDllRel 
easefield.obj"  "ObjDllReleaselargeobject.obj"  "ObjDllReleasenontransaction. 
obj"  "ObjDllReleasenotification.obj"  "ObjDllReleasenotify-listen.obj"  "ObjD 
llReleasepipeline.obj"  "ObjDllReleaseprepared_statement.obj"  "ObjDllRelease 
result.obj"  "ObjDllReleaserobusttransaction.obj"  "ObjDllReleasestatement_par 
ameters.obj"  "ObjDllReleasestrconv.obj"  "ObjDllReleasesubtransaction.obj"  " 
ObjDllReleasetablereader.obj"  "ObjDllReleasetablestream.obj"  "ObjDllRelease 
tablewriter.obj"  "ObjDllReleasetransaction.obj"  "ObjDllReleasetransaction_ba 
se.obj"  "ObjDllReleasetuple.obj"  "ObjDllReleaseutil.obj"  "ObjDllReleaselib 
pqxx.obj" /out:"liblibpqxx.dll" /implib:"liblibpqxx.lib" 
  Creating library liblibpqxx.lib and object liblibpqxx.exp 

[plain] view plaincopyprint?

link.exe kernel32.lib ws2_32.lib advapi32.lib /nologo /dll /machine:I386

shell32.lib secur32.lib wldap32.lib /libpath:"C:hisql-x86-2.0.1"lib libpq.lib

"ObjDllReleasebinarystring.obj"  "ObjDllReleaseconnection.obj"  "ObjDllRelea

seconnection_base.obj"  "ObjDllReleasecursor.obj"  "ObjDllReleasedbtransactio

n.obj"  "ObjDllReleaseerrorhandler.obj"  "ObjDllReleaseexcept.obj"  "ObjDllRel

easefield.obj"  "ObjDllReleaselargeobject.obj"  "ObjDllReleasenontransaction.

obj"  "ObjDllReleasenotification.obj"  "ObjDllReleasenotify-listen.obj"  "ObjD

llReleasepipeline.obj"  "ObjDllReleaseprepared_statement.obj"  "ObjDllRelease

result.obj"  "ObjDllReleaserobusttransaction.obj"  "ObjDllReleasestatement_par

ameters.obj"  "ObjDllReleasestrconv.obj"  "ObjDllReleasesubtransaction.obj"  "

ObjDllReleasetablereader.obj"  "ObjDllReleasetablestream.obj"  "ObjDllRelease

tablewriter.obj"  "ObjDllReleasetransaction.obj"  "ObjDllReleasetransaction_ba

se.obj"  "ObjDllReleasetuple.obj"  "ObjDllReleaseutil.obj"  "ObjDllReleaselib

pqxx.obj" /out:"liblibpqxx.dll" /implib:"liblibpqxx.lib"

Creating library liblibpqxx.lib and object liblibpqxx.exp

link.exe kernel32.lib ws2_32.lib advapi32.lib /nologo /dll /machine:I386

shell32.lib secur32.lib wldap32.lib /libpath:"C:hisql-x86-2.0.1"lib libpq.lib

“ObjDllReleasebinarystring.obj” “ObjDllReleaseconnection.obj” “ObjDllRelea

seconnection_base.obj"  "ObjDllReleasecursor.obj"  "ObjDllReleasdbtransactio

n.obj"  "ObjDllReleaseerrorhandler.obj"  "ObjDllRelease except.obj"  "ObjDllRel

easefield.obj"  "ObjDllReleaselargeobject.obj"  "ObjDllReleasenontransaction。

obj"  "ObjDllReleasenotification.obj"  "ObjDllReleasenotify-listen.obj"  "ObjD

llReleasepipeline.obj"  "ObjDllReleaseprepared_statement.obj"  "ObjDllRelease

结果.obj"  "ObjDllReleaserobusttransaction.obj"  "ObjDllReleasestatement_par

ameters.obj"  "ObjDllReleasestrconv.obj"  "ObjDllReleasesubtransaction.obj"  "

ObjDllReleasetablereader.obj"  "ObjDllReleasetablestream.obj"  "ObjDllRelease

tablewriter.obj"  "ObjDllReleasetransaction.obj"  "ObjDllReleasetransaction_ba

se.obj"  "ObjDllReleasetuple.obj"  "ObjDllReleaseutil.obj"  "ObjDllReleaselib

pqxx.obj" /out:"liblibpqxx.dll" /implib:"liblibpqxx.lib"

创建库 liblibpqxx.lib 和对象 liblibpqxx.exp 最终会在lib目录下生成：

[纯文本]查看纯文本？

D:Projectshisql.svntrunklearninglibpqxx-4.0>dir/b/s lib

D:Projectshisql.svntrunklearninglibpqxx-4.0liblibpq.dll

D:Projectshisql.svntrunklearninglibpqxx-4.0liblibpq.lib

D:Projectshisql.svntrunklearninglibpqxx-4.0liblibpqxx.dll

D:Projectshisql.svntrunklearninglibpqxx-4.0liblibpqxx.dll.manifest

D:Projectshisql.svntrunklearninglibpqxx-4.0liblibpqxx.exp

D:Projectshisql.svntrunklearninglibpqxx-4.0liblibpqxx.lib

D:Projectshisql.svntrunklearninglibpqxx-4.0liblibpqxxD.dll

D:Projectshisql.svntrunklearninglibpqxx-4.0liblibpqxxD.dll.manifest

D:Projectshisql.svntrunklearninglibpqxx-4.0liblibpqxxD.exp

D:Projectshisql.svntrunklearninglibpqxx-4.0liblibpqxxD.ilk

D:Projectshisql.svntrunklearninglibpqxx-4.0liblibpqxxD.lib

D:Projectshisql.svntrunklearninglibpqxx-4.0liblibpqxxD.pdb

D:Projectshisql.svntrunklearninglibpqxx-4.0liblibpqxx_static.lib

D:Projectshisql.svntrunklearninglibpqxx-4.0liblibpqxx_staticD.lib

D:Projectshisql.svntrunklearninglibpqxx-4.0libmsdia80.dll

D:Projectshisql.svntrunklearninglibpqxx-4.0>dir/b/s lib

D:Projectshisql.svntrunklearninglibpqxx-4.0liblibpq.dll

D:Projectshisql.svntrunklearninglibpqxx-4.0liblibpq.lib

D:Projectshisql.svntrunklearninglibpqxx-4.0liblibpqxx.dll

D:Projectshisql.svntrunklearninglibpqxx-4.0liblibpqxx.dll.manifest

D:Projectshisql.svntrunklearninglibpqxx-4.0liblibpqxx.exp

D:Projectshisql.svntrunklearninglibpqxx-4.0liblibpqxx.lib

D:Projectshisql.svntrunklearninglibpqxx-4.0liblibpqxxD.dll

D:Projectshisql.svntrunklearninglibpqxx-4.0liblibpqxxD.dll.manifest

D:Projectshisql.svntrunklearninglibpqxx-4.0liblibpqxxD.exp

D:Projectshisql.svntrunklearninglibpqxx-4.0liblibpqxxD.ilk

D:Projectshisql.svntrunklearninglibpqxx-4.0liblibpqxxD.lib

D:Projectshisql.svntrunklearninglibpqxx-4.0liblibpqxxD.pdb

D:Projectshisql.svntrunklearninglibpqxx-4.0liblibpqxx_static.lib

D:Projectshisql.svntrunklearninglibpqxx-4.0liblibpqxx_staticD.lib

D:Projectshisql.svntrunklearninglibpqxx-4.0libmsdia80.dll

下边来看看最简单的示例：

iihero=# 创建用户 foo 密码 'foo1';

创建角色

[sql] 查看 plaincopyprint?

iihero=>创建表 t(id int 主键, col2 varchar(32));

注意：  CREATE TABLE / PRIMARY KEY 将要为表 "t" 创建隐含索引 "t_pkey"

创建表

iihero=>编码

GBK

iihero=> insert into t value(1 ,'不同类型的列表');

插入 0 1

iihero=>从 t 中选择*；

id |      列2

--------------------------------

1 | 不同类型的列表

(1行记录)

iihero=>创建表 t(id int 主键, col2 varchar(32));

注意：  CREATE TABLE / PRIMARY KEY 将要为表 "t" 创建隐含索引 "t_pkey"

创建表

iihero=>编码

GBK

iihero=> insert into t value(1 ,'不同类型的列表');

插入 0 1

iihero=>从 t 中选择*；

id |      列2

--------------------------------

1 | 不同类型的列表

(1行记录)

将编译出来后的include、lib目录提取到固定的目录，和你原来的postgresql的include和lib目录，可以合到一起。给开发使用。

下边是一个最简单的示例：

[cpp] 查看纯文本？

#include <iostream></p>
<p>#include <pqxx/pqxx></p>
<p>int main()</p>
<p>{</p>
<p>pqxx::connection conn("dbname=iihero hostaddr=127.0.0.1 user=foo 密码=foo1" );</p>
<p>if(conn.is_open())</p>
<p>{</p>
<p>std::cout << “连接成功！” << std::endl;</p>
<p>std::cout << conn.options()<<std::endl;</p>
<p>}</p>
<p>其他</p>
<p>{</p>
<p>std::cout << “出了点问题……哎呀”<< std::endl;</p>
<p>}</p>
<p>pqxx::work w(conn);</p>
<p>pqxx::result res = w.exec("SELECT 1");</p>
<p>w.commit();</p>
<p>std::cout << res[0][0].as<int>() << std::endl;</p>
<p>}</p>
<p>